I’ve never had to go above 4.
Your lights seem very bright to me and raising the bias seems to have helped but it might cause problems elsewhere with shadows.
I often find it is a act of balancing several things.

I actually dialed them down a lot. The Backlight is typically very bright. I have the UE2 set at 52.6%. The Key Light is at 75%, Fill: 25%, and Backlight at 150% (that’s a normal settup with the back light double the intensity of the key light).

I used some of the tricks I learned at Dreamlight to get this settup. Not all, mind you, but some.

okay, I KNOW where those lines came from: It was the shadow softness. So: here are my materials, with the specular dialed down to 50%. The Shadows at 1% soft on Shadow Mapped Shadows… I’ll be replacing the lightset I have posted on ShareCG and I’ll be posting these materials for y’all to play with.

Sorry no it doesnt always fit I have my shadow softness up high and don’t get the lines if I do I reduce the Subsurface scale.
That render above shadow softness was at about 30%

When this render finishes (and after I’ve had some sleep) I’ll run some more test on other scenes I have that have the stripes but my current render seems to have improved by dropping the shadowsoftness from 60 to 30% (I know maybe 60% was a bit high )

besides at the very least weve established that shadowsoftness is a factor with SSS just like shadow bias.